discord py reply to message

1@bot.event
2async def on_message(message):
3    if message.content == "pong":
4        await message.channel.send('ping')

1await client.fetch_channel(channelId)

1channel.guild

1await ctx.reply('Hello!')
2

1@bot.event
2async def on_message(message):
3    if isinstance(message.channel, discord.channel.DMChannel) and message.author != bot.user:
4        await message.channel.send('This is a DM')